Improvement in thread-cutting tools for metal-screw machines



Thread-Cutting W mmw:

A-.[JOHNSTON. I v Tool for Metal-Screw Machines.

Patehted Jam 28. 1879.

UNITED STATES PATENT ALLEN JOHNSTON, OF OTTUMVVA, IOWA. I

IMPROVEMENT IN THREAD-CUTTING TOOLS FOR METAL-SCREW MACHINES.

Specification forming part of Letters Patent No. 211,742, dated January 28, 1879; application filed November 8, 1878.

To all whom it may concern: 1

Be it known that I, ALLEN JOHNSTON, of O'ttumwa, in the county of WVapello and State of Iowa, have invented a new and useful Improvement in Thread-Cuttin g Tools for Metal- Screw Machines, which improvement is fully set forth in the rollowin g specification:

This invention relates to screwcuttin g tools, to be used in the manufacture of screws by machinery, for cutting the thread upon the wire, which is grasped and revolved by a suitable chuck on a hollow lathespindle, the tool itself being presented to the wire to act thereon, and withdrawn when the screw-cutting die hasbeenreleased from the newly-formed thread by suitable mechanism.

The invention consists in mechanism carried by the body of the tool for releasing the screw from the die after the thread is cut thereon without reversing the chuck, by revolving the die in the same direction and at a greater speed than the chuck revolves in means for deriving the motion for revolving the die faster than the chuck, and in the same direction thereas, directly from the chuck or chuck-spindle by engagement therewith; in means for permitting to the die and its holder a free endwise movement within the body of the tool during the unwinding of the screw; in the construction and combination of mechanism, and in the tool itself composed of the various parts, as hereinafter more fully described.

In the drawings, Figure 1 is a perspective view. Fig. 2 is a longitudinal central section. Fig. 3 is a cross-section on line X K, Fig. 2; and Fig. 4, a perspective view of two of the gears employed, showing the projections on the sides.

A represents the body or shell of the tool, made hollow throughout its entire length, and being slotted below and provided with an opening above. At one end it is turned ofi' to form a shank, a, for holding it in a socket in the turret.

B is a tube or sleeve resting inv one end of the body of the tool and free to turn therein. It has a groove, 1), turned about it, into which a screw, 1), passing through the wall of the tool-shell, enters, and while allowing the rotation of said tube or sleeve prevents the removal thereof. 0 is the dieholder. It has its bearing in the sleeve B, in which it is free to rotate.

D is the die, secured in an enlarged portion of the holder. E is the cap or sleeve, provided with one or more jaws or projections, e, and v secured on the end of the sleeve or tubular bearing B by screws 0, which pass through.

slots in the cap and permit its adjustment 011 the tubular bearing. F is a gear or spur-pinion, the journals of which restin bearings in projections a on the body of the tool. In one bearing is a spring, f, and upon the face of the pinionF, opposite thereto,is aprojectiomf.

G is a pinion free to revolve on one of the journals of the gear F. It is provided, on the side next the said gear, with a projection. This projection and the one f on the pinion F have inclined faces on one side, so as to permit the gears to slip past each other, the spring f yielding sufficiently therefor, so as not to communicate the motion of the gear G to the gear F. The other sides of the projections are adapted to engage, so that the motion of the gear F is communicated to the gear Gr.

H is a spur-gear secured to the tubular hearing B, and the gear F engages therewith. I is a long spur gear or pinion secured to the die-holder. It engages with the pinion G. It is provided with a projection, 15. K is a hollow tube or sleeve, into which one end of the die-holder projects, and is sustained thereby. It is connected by a pin, 70, passing through a slot in the body of the tool, with the slide L,

low body of the tool, and at the other against a cap, 70 screwed into the end of the hollow tube K.

A pin, N, pressed upward by a spring, at, serves to retain the tube K in position against the retraction of the spring m. The pin Nrests in the groove 1) on the tubular bearing B, and

is withdrawn therefrom by a key, a, which works in a slot cut in the projection l of the slide L, the inclined plane formed by a notch cut in the under side of said key serving to draw the pin down against the spring a.

O is a series of pins, located in holes in the tool-body, and pressed outward by springs located j ust beyond their rear ends. Their points press against a shoulder on the end of the tubular bearin In operation the tool is placed and secured holder are drawn forward by the newly-formed screw-thread, (sufficient endwise movement of the die-holdcr being permitted by the construction and arrangement of parts,) and the projection on the pinion I is drawn out of engagement with the clutch formed by the projection 70 on the sleeve K, sothat the die revolves freely with the wire, the motion not being communicated to the tubular bearing through the gears Gr and F,'as before explained. I

When the tool is again fed forward the dieholder is pressed back, and the projections k engage, and the cutting of the screw-thread reconnnences. When this operation is completed the pin N is withdrawn from the groove in the tubular bearing of the die-holder, and the sleeve K is withdrawn, so as to allow the die-holder to revolve freely, and also to permit thereto a free endwise movement within its bearin At the same time the tubular bearing is forced forward by the springs 0, acting on the pins 0, and the jaws c of the cap or sleeve E are brought into engagement with the clampin gjaws of the chuck, or with pro- 'jections thereon, causing the revolution of the tubular bearing with the chuck.

The tubular bearing revolving with th e chuck communicates motion, through the gears H, F, G, and I, to the die-holder. The gears H and G are larger than the gears F and I, respectivel y, an d amore rapid motion is therefore communicated to the die-h older than the chuck and tubular bearing have, so that the die has a forward rotation relatively to the wire, which causes the unwinding of the diefrom the screw. The die-holder is, during the unwinding of the screw, free to move in the direction of its length, the long spur-pinion I serving to permit this mot-ion without causing the disengagement of the gears. During this operation the turret remains stationary, the die-holder being moved backward in its bearing by the action of the screw-thread in the die, and the freedom of motion preventing all burring and jamming of the thread, which is-liable to be made when the die-holder has a positive motion backward in unwinding the screw.

After the release of the screw the turret is moved backward, and revolves to bring another tool into position. Before the screwcutting tool is again brought into position to act on the'wire, the projection l on the slideL is brought into contact with a cam or other mechanism, such as a lever or .series of levers located on the lathe, and pushed forward thereby into position for cutting a thread on the next screw, and is retained in such position by the pin N.

The cap or sleeve E, coming into contact with the face of the chuck, prevents the cutting of the thread beyond a certain point.

To regulate the distance to which the cutting shall extend, and thus to vary the length of the screw-thread, the sleeve E is made adjustable with reference to the tubular holder by means of the slots therein and the screws 6.

The cap E may, if desired, be made in one piece with the tubular bearing but the formation of the cap and bearing in separate pieces and the adjustment as described is regarded as the best construction.

The key a is operated to withdraw the pin N by being forced, by the forward motion of the turret, against a projection on the slide-rest or body of the lathe. The projection is preferably secured to one of the tool-posts of the slide-rest.

Instead of using the key a with the notch, as shown, I may employ a bell-crank lever, or other mechanical device, to operate the withdrawal of the pin N and the release of the clutching devices. Y

I have shown the cap E as provided with three jaws; but this number may be increased or diminished without altering the machine,

as I have found one jaw to answer the purpose well. j

The pins 0 and springs 0 are notessential to the successful working of the machine, and

may be omitted. Their object is to force the cap E of the tubular bearing forward quickly to insure a speedy and certain engagement of the jaws thereof with the jaws or projections of the chuck.

Having described my invention,what I claim and desire to secure by Letters Patent, is-

1. In a screw-cutting tool, the combination, with the die and its holder and the body of the tool, of mechanism, substantially as described, carried by the body of the tool, adapted to revolve the die in the same direct-ion and at a greater speed than the chuck to unwind the screw, as set forth.

2. The combination, with the die-holder o a screw-cutting tool and mechanism, substantially as described, adapted to revolve said die-holder in the same direction as the chuck, but at a greater speed, of means, substantially as set forth, adapted to engage with the chuck or chuck-spindle, and derive directly therefrom the motion for operating the mechanism for revolving the die-holder, substantially as specified.

3. In combination with the die-holder and body or shell of a screw-cutting tool, of mechanism, as described, carried by the body of the tool, and adapted to revolve the die-holder in the same direction as the ehuck,but at a greater speed, and to permit to the die-holder a free movement within the body of the tool in either direction in line of its length in unwinding the screw, substantially as set forth.

4. In a screw-cutting tool of the character described, the combination, with the die and its holder, the tubular bearing of the die-holder, and mechanism for imparting to the die the motion of the tubular bearing, of a cap or sleeve secured to the tubular bearing, and provided with one or more jaws, clutches, or projections adapted to engage with the grasping jaws or projections on the chuck, substantially as set forth.

5. In a screw-cutting tool, the combination, with the die and its holder and the tubular bearing surrounding the die-holder, of a cap or sleeve secured to the tubular bearing, and adjustable relatively thereto to regulate the length of the screw-thread, substantially as set forth.

6. The combinatiomwith the die-holder provided with a spur-pinion, of the tubular bearing surrounding the same, having at one end a spur-pinion connected, by intermediate gearing carried by the body of the tool, with the pinion of the die-holder, the parts being constructed and arranged to impart, by the revolution of the tubular bearin g, to the dieholder a rotation at a greater velocity in the same direction as the chuck, substantially as set forth.

7. The combination,with the dieholder provided with a long spur-pinion, of the tubular bearing surrounding the same, having at one end a spur-pinion connected, by intermediate gearing carried by the body of the tool, with the pinion of the die-holder, the parts being constructed and arranged to impart, by the revolution of the tubular bearing, to the dieholder a rotation at a greater velocity in the same direction as the chuck, and at the same time to permit a free longitudinal motion to the die-holder, and having at the other end a cap or sleeve adapted to engage with and receive motion from the chuck, substantially as set forth.

S. The combination, with the die-holder and body of a screw-cutting tool, and with automatic clutching devices, located within the body of the tool, and adapted to retain the die [and its holder stationary during the approach of the'turret to the chuck, or to permit the free revolution thereof when fed too slowly for the proper cutting of the thread, of automatic releasing devices adapted to withdraw or allow the withdrawal of the said clutching devices to permit a free endwise movement of the die-holder in its bearing during the unwinding of the screw, substantially as set forth.

9. The herein described tool for cutting screws, consisting of the die-holder having at its inner end a long spur-pinion, the tubular bearing surrounding said holder, having at one end a spur-pinion connected, by intermediate gearing carried by the body of the tool, with the pinion on the die-holder, and at the other end a cap or sleeve to en gage with and receive motion from the chuck, the clutching devices to retain or permit the rotation of the die-holder during the operation of cutting the thread, the releasing devices to allow the withdrawal of the clutching devices and permit a free endwise motion to the die-holder during the operation of unwinding the die from the screw-thread, and the body or shell of the tool, arranged and adapted to operate as set forth.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

ALLEN JOHNSTON. Witnesses:

E. A. DICK, (Jr-ms. J. HEDRICK. 

